Android Retrofit: missing method body or declare abstract

I am writing an Android application that will use Retrofit to make API requests.

I have a helper class:

public class ApiService {
    public static final String TAG = ApiService.class.getSimpleName();

    public static final String BASE_URL = "https://myapiurl.com";

    public static void testApi(){
        ApiEndpointInterface apiService = prepareService();
        apiService.ping(new Callback<Response>() {
            @Override
            public void success(Response apiResponse, retrofit.client.Response response) {
                Log.e(TAG, apiResponse.toString());

            }

            @Override
            public void failure(RetrofitError error) {
                Log.e("Retrofit:", error.toString());

            }
        });

    }

    private static ApiEndpointInterface prepareService() {
        RestAdapter restAdapter = new RestAdapter.Builder()
                .setEndpoint(BASE_URL)
                .build();
        ApiEndpointInterface apiService =
                restAdapter.create(ApiEndpointInterface.class);

        restAdapter.setLogLevel(RestAdapter.LogLevel.FULL);
        return apiService;
    }

}

      

        
        
        
      

    

And my actual implementation of the Appendix is ​​simple:

public class ApiEndpointInterface {

    @GET("/v1/myendpoint")
    void ping(Callback<Response> cb);
}

      

        
        
        
      

    

The problem is I can't build the project, I get the error:

Error:(12, 10) error: missing method body, or declare abstract

      

        
        
        
      

    

Referring to my ApiEndpointInterface class.

Any idea what's going on?